Network recovery after massive failures

This paper addresses the problem of efficiently restoring sufficient resources in a communications network to support the demand of mission critical services after a large scale disruption. We give a formulation of the problem as an MILP and show that it is NP-hard. We propose a polynomial time heuristic, called Iterative Split and Prune (ISP) that decomposes the original problem recursively into smaller problems, until it determines the set of network components to be restored. We performed extensive simulations by varying the topologies, the demand intensity, the number of critical services, and the disruption model. Compared to several greedy approaches ISP performs better in terms of number of repaired components, and does not result in any demand loss. It performs very close to the optimal when the demand is low with respect to the supply network capacities, thanks to the ability of the algorithm to maximize sharing of repaired resources

On critical service recovery after massive network failures

This paper addresses the problem of efficiently restoring sufficient resources in a communications network to support the demand of mission critical services after a large-scale disruption. We give a formulation of the problem as a mixed integer linear programming and show that it is NP-hard. We propose a polynomial time heuristic, called iterative split and prune (ISP) that decomposes the original problem recursively into smaller problems, until it determines the set of network components to be restored. ISP's decisions are guided by the use of a new notion of demand-based centrality of nodes. We performed extensive simulations by varying the topologies, the demand intensity, the number of critical services, and the disruption model. Compared with several greedy approaches, ISP performs better in terms of total cost of repaired components, and does not result in any demand loss. It performs very close to the optimal when the demand is low with respect to the supply network capacities, thanks to the ability of the algorithm to maximize sharing of repaired resources

Evaluation of non-linear phase space distortions via frequency analysis

Several methods have been developed recently to measure the frequencies of a time series to much higher precision than ordinary FFT. The decomposition of tracking or experimental data into a Fourier transform can therefore also be done with largely enhanced precision. On the one hand this allows to free these data from complicated phase space distortions. On the other hand, these high precision spectrum lines can be interpreted as being the result of the excitation of certain resonances. In this report we study how this information can be used to tackle resonances. It has to be stresses that this techniques requires no knowledge concerning the simulation model or the accelerator being studied. the only input needed is a series of tracking data or, in the case of the experiment, a set of turn-by-turn data after kicking the beam

Normal form via tracking or beam data

Normal Form is a powerful tool to analyse the nonlinear content of a complicated system like an accelerator with its many thousands of high order multipolar errors. This technique needs as input a mapping from the initial to the final coordinates. Unfortunately, a map of an accelerator is not known beforehand but has to be determined for a complete lattice of the accelerator including all calculated and/or measured error tables of the guiding and focussing magnet elements. It is however possible to obtain turn-by-turn position data of a kicked beam for many turns. In various experiments at existing accelerators it has been shown that these data are equivalent to tracking data produced by simulation programs. In this report we will demonstrate how tracking data can be used to determine, with excellent precision, the coefficients of the generating function. The well tested Normal Form tools can then be used to construct the underlying Hamiltonian and the map. The essential tool is the recently developed frequency analysis which allows for a very precise determination of the tunes using beam or tracking data

REAL OPTION MODELS FOR SIMULATING DIGESTER SYSTEM ADOPTION ON LIVESTOCK FARMS IN EMILIA-ROMAGNA

Innovation and new technology adoption represent two central elements for the enterprise and industry development process in agriculture. The objective of this paper is to develop a farmhousehold model able to simulate the impacts of uncertainty in SFP, the selling price of energy and agricultural product prices parameters on the adoption of methane digester for biogas production. The model implemented is based on a real option approach that includes investment irreversibility and stochasticity in relevant parameters. The results show the relevance of uncertainty in determining the timing of adoption and emphasise the importance of predictability as a major component of policy design

Деякі питання структурної теорії додавання множин

(uk) Доведено теорему про існування множин, а також знайдені значення у вершинах критичних трикутників.(en) Generalization of theorem on the existence. The meanings at the axis of critical triangles have been found

Dynamic Effects of Wind Loads on a Gravity Damper

AbstractThe gravity damper is safety device used for the air treatment that prevent overpressure inside the unit through the opening. It is a normally closed valve under the effect of the gravity force, which, under the action of the incident air flow, allows to manage any excess mass. Clearly, although the device is rather simple and therefore reliable, the operating conditions may prove burdensome, especially if the gravity dampers are applied to installations of energy transformation, such as the gas turbines; this is mainly due to the need to develop large masses of air at speeds rather incurred. This article describes an experiment carried out on a gravity damper designed to be installed in a gas turbine. The characterization has been performed in numerical (CFD-FEM), considering both the mode shapes and the natural frequencies of the device in working condition as well as any phenomenon of detachment of the fluid that can trigger vortex shedding and subsequently validated in the wind tunnel facilities of the University of Perugia. In particular, what is wanted to be highlighted is the fact that, after a preliminary analysis, it has been clearly evident that, under the operating conditions, the structure would be affected by phenomena of vortex shedding. The shedding frequency is next to some natural frequencies of the structure, with obvious repercussions on the integrity of the structure. An experimental vibration analysis performed in the wind tunnel at flow regime has in fact allowed to identify the phenomenon of lock-in

Egg quality from nera atriana, a local poultry breed of the Abruzzo region (Italy), and isa brown hens reared under free range conditions

The selection and diffusion in the poultry sector of hybrid breeds able to produce higher amount of meat and eggs, led over time to the erosion of genetic resources. One of the strategies that can be applied in order to stem such phenomenon, concerns the valorization of the animal products, meat or eggs, obtained from indigenous poultry breeds. Therefore, the aim of this study is to characterize the qualitative aspects of eggs obtained from the Nera Atriana hen, an Italian indigenous laying hen characteristic of the Abruzzo region, making a direct comparison with a commercial hybrid reared in the same environment and applying the same feeding protocol. The trial was conducted for a period of 5 months (from March to July 2019), in which 6 egg samplings were performed (one at the beginning and additional 5 on a monthly basis); each sampling involved the collection of 15 eggs per group of animals for a total of 90 eggs per genotype. Eggs were specifically subjected to evaluations of the physical parameters, including the yolk color, and analyses aimed at determining the content of total lipids, cholesterol, and β-carotene. In addition to this, the fatty acids profile and the electrophoretic pattern of the globular proteins of the yolk were characterized. Eggs from hybrid hens were characterized by higher total weight with significantly higher values specifically associated to albumen and yolk weight and to the albumen percentage. In the eggs obtained from the local hen, higher relative percentages were instead found in the quantity of shell and yolk; furthermore, in the same samples was observed a higher yolk redness, a cholesterol concentration tending to be lower although not significant (p = 0.0521), and a greater amount of saturated fatty acids which could justify a lower susceptibility of the food to oxidative processes following transformation with heat treatments. With regard to the fatty acid composition, differences were specifically observed for palmitic (C16:0) and palmitoleic (C16:1 cis-9) acids that showed higher relative percentages in eggs from local breed, and for the oleic acid (C18:1 cis-9) which was more represented in eggs from commercial hens. In conclusion, some interesting nutritional features, in a preliminary way, have been highlighted that could lead the consumer to prefer these “niche” products over those obtained from commercial hybrids